Almost a million residents of Boston and surrounding towns were ordered to stay in their homes on Friday as the hunt for one of the suspects in the marathon bombing continued.

The suspects were identified as brothers, reportedly of Chechen origin. Dzhokhar Tsarnaev, 19, remains on the loose. Law enforcement officials said he was the suspect wearing the white hat in images released by the FBI on Thursday of the bombing suspects. His elder brother Tamerlan Tsarnaev, 26, was killed in the early hours of Friday after a car chase and shootout with police.

Massachusetts governor Deval Patrick warned people to remain indoors "with their doors locked" until further notice, after a night of high drama during which a campus police officer at the Massachusetts Institute of Technology was shot dead.

"We're asking people to shelter in place: in other words, to stay indoors, with their doors locked, and not to open the door for anyone other than a properly identified law enforcement officer," Patrick said.

"That applies here in Watertown, Cambridge, Waltham, Newton, Belmont and at this point all of Boston. All of Boston. This is a serious situation. We're taking it seriously; we're asking the public to take it seriously as well."

The announcement, made during a brief press conference in Watertown just after 8am on Friday, dramatically extended the lockdown area to over 930,000 across the six neighborhoods. Earlier, residents in Watertown, population 32,000, had been told to stay inside, and public transport systems in and around Boston had been shut down.

"There is a massive manhunt underway, [and] a lot of law enforcement involved in that," Patrick said. "We've got every asset that we can possibly muster on the ground right now."

AP reported on Friday that the father of the suspect had described his son as an accomplished medical student and a "true angel".

suspect 2 boston bombing Photograph: fbi.gov

According to his account on the Russian social networking site Vkontakte, Dzhokhar Tsarnaev, pictured, graduated from the Cambridge Rindge & Latin School, a Massachusetts high school, in 2011, and attended School No 1 in Makhachkala, the capital of Dagestan, from 1999 to 2001.

He appears to have been a good student, having received a $2,500 scholarship from the city of Cambridge in 2011 to pursue college. He was also named a wrestling all-star at his high school the same year.

On his VKontakte page, Tsarnaev says he considers "career and money" most important in life. As his worldview, he wrote: "Islam".

The page says Tsarnaev speaks English, Russian and Chechen, and belongs to a number of groups devoted to Chechnya. Dagestan, a republic neighbouring Chechnya, maintains a small Chechen minority.

Tsarnaev was born on 22 July 1993, just before a fierce battle for independence broke out in the republic of Chechnya, attempting to secede from Russia in the wake of the Soviet Union's collapse. Over time, the independence movement grew increasingly Islamist in character. Largely quashed by Moscow, a low-level insurgency persists in Chechnya and has leaked into neighbouring Dagestan.

The Boston bombing suspects were of Chechen origin

On VKontakte, Tsarnaev follows several pages devoted to Islam. He also lists one of his favorite songs as Hey Sexy Lady by Shaggy.

The drama began around 10:20pm on Thursday night when the men committed an armed robbery at a 7-11 store near MIT in Cambridge. Minutes later, the MIT police officer was found dead in his car with multiple gunshot wounds, according to a statement from law enforcement officials in Cambridge. The men then hijacked a black Mercedes SUV, holding the driver at gunpoint for about 30 minutes before releasing him uninjured. Police pursued the vehicle into Watertown, with the men reportedly throwing explosives from the car and exchanging fire with officers.

The dead officer was named by the Middlesex County district attorney as Sean Collier, 26, of Somerville.

Boston's CBS affiliate WBZ broadcast an interview obtained by a local station in Maryland with a man, Alvi Tsarni, who said he was an uncle of the suspects.

Tsarni told the reporter that he had heard about his nephews' involvement this morning from a sister-in-law. "She was crying and she said that Tamerlan was killed."

Tsarni said the brothers, Dzhokhar and Tamerlan, "grew up in Kyrgyzstan" and came to the United States "seven or eight years ago."

'It's unbelievable, it's not possible'

In imperfect English, Tsarni, who said he had lived in the United States for 10 years, said he had not spoken with the brothers for a long time because of "problems family." Then "yesterday he called me," Tsarni said – he appeared to be referring to Tamerlan – "and said 'Forgive me, and we will talk to this now. From now we will be together ever."

The reporter told Tsarni she was sorry for his loss.

"I'm sorry too, if he did this one I'm sorry too. It's crazy. It's not possible. I can't believe it … It's crazy. It's unbelievable.

The scene of the shootout involving the Boston bomber suspects in Watertown. Photograph: Barcroft Media

According to eyewitness reports, the men got out of the car and threw an explosive device at police. Tamerlan Tsarnaev then ran towards police where he was either tackled or shot. His brother got back in the car, and drove it straight through the police line, heading west.

In the shootout, another officer, from the Massachusetts Bay Transportation Authority, was seriously wounded and is in hospital, it was revealed at the briefing on Friday morning.

In the photographs released by the FBI on Thursday, Dzhokhar Tsarnaev is seen wearing a grey hoodie and a white cap turned backwards. He has long, curly dark hair, and walked through the marathon crowd about five paces behind his brother.

Police have said Tamerlan Tsarnaev was spotted placing a black bag outside the Forum restaurant, close to one of the bomb epicentres shortly before it detonated. That video has not been made public.